30
COMpOnent aCCess
REMEMBER THAT HIGH VOLTAGES ARE EXPOSED WHEN THE CASE IS REMOVED AND THE UNIT IS
PLUGGED INTO THE POWER.
to drain the alumina fluidising medium
a) This is best done when the bath is cool as hot alumina can cause severe burns.
b) Ensure that the fluidisation air is turned off at the valve on the flowmeter (21), remove the drain cap
(23) situated at the bottom rear of the unit. CAUTION, CAP MAY BE HOT. If the flowmeter has not
been turned off and the unit is connected to the air supply, a jet of alumina will be released when
the cap is removed.
c) Fit the drain extension tube. Avoid over tightening. The bath may now be drained by very slowly
turning on the fluidising air at the flowmeter until a steady flow of alumina is obtained. Hot alumina
should be drained into a well insulated container of suitable material to avoid fire hazards. When
the bath is empty remove the drain extension tube, clean the thread of the drain cap, and refit.
Note: Before replacing the thermocouple or the heaters the bath should be emptied of alumina, see
para. 1 above. The air and electrical supplies must be disconnected at all times when servicing the
system.
to replace the thermocouple
a) Remove the top panel (1) by removing the screw at the left hand bottom corner, push up and
pull out the panel.
b) Remove the three screws securing the front panel (5) along the upper edge. DO NOT DISTURB
SCREW WITH EARTH SYMBOL ALONGSIDE IT. Remove the knurled nut from the extraction
switch (22) and lower the panel.
c) Disconnect the thermocouple wires from the rear of the temperature controller (16) taking note
of the polarity for reconnection.
d) Slacken the thermocouple lock nut (52) back about 10mm. Unscrew the parallel bush (50) and
remove the thermocouple (51). Access may be improved by disconnecting the hose (31) from
the air mover (32).
e) Reverse the operation for replacing the thermocouple ensuring that it does not touch the
heater and that the sheath is clear of any electrical parts.
to replace the heaters
a) Remove the upper front panel (1) as above.
b) Turn the unit on its back to gain access to the heater terminations.
c) Disconnect the wiring from the heaters (47) and remove the nuts (45) and washers (46) from
the heater unions.
d) Replace the unit on its feet and withdraw the heater through the top aperture.
e) Reverse the operation to replace the heater fitting new seal washers (44) to the heater union. It
may be necessary to spring the heater in order to pass the terminations through the holes.
Should the heater lay too close to the wall of the inner container at the bottom, pull it away
gently.
